Two-part expanding foam seats (again; maybe FAO Myles?)

[Mankee]

I'm going to order some two-part expanding foam from CFS soon to make a complete seat to replace a Tillett, in a normal S3 chassis. Will I need the 5-kg pack or can I get away with a 2-kg pack? I'm a bit under 80kgs, average build, I would say.

Also, any recommendations on the strong bag(s) required, with the least risk of splitting and spaffing uncontrollable gobs of hot foam all over my car?

[mikecocker]

I used a survival bag from Go Outdoors, very big and very strong and just over 2 quid. I think you'll need the 5kg pack to be on the safe side, you'll kick yourself if you have to order another pack half way through the process.

[Grubbster]

Hi Mike, did you do yours as a single pour or did you do the base and back separately? I'm going to make one for the snot. 

[Richard Price]

I've made a couple of foam seats.

I've made a barrier (fabricated from stiff cardboard) on both occasions to prevent the foam going too far into the foot well.

Additionally, as a sit quite well forward and upright, I've also use a sheet of Celotex type PU foam board to form the first part of the back rest part.

I always remove the harnesses, rather than trying to work around them.

I've made my seats as two separate parts. That way they are easily removable.

If the car has a standard, padded, tunnel top, then the whole seat can get jammed in place (under the lip of the tunnel top), so it's best to make sure the tunnel top is not fixed in place, and is free to lift.

 

[mikecocker]

Steve, I made mine in one piece but did 3 pours to achieve this. I put a small square of polystyrene inside the bag under my butt to achieve the right height and then as I poured the back I gently rested back against the expanding foam while holding the steering wheel as a bit of support. As Richard says, remove the tunnel top and I also taped some card over the seat belt fixing holes to prevent the foam expanding and locking the seat in place. 

[Paul Deslandes]

If they haven't already, anyone planning to do this really should search and read the BC archives on this topic.  There are at least 10 years worth of threads (including the hilarious canoe story) which give excellent advice and details re measuring the mix proportions, mixing methods, ambient temperature, having a 'pee' before you start etc.

[sjmmarsh]

As search isn't working too well:

• remember to to fully depress the pedals whilst it is setting
• if the fit isn't right you can always carve a bit off and add a bit more liquid foam to have another go
• you can get some plastic dust sheets to protect the car from any overspill - they are not expensive

steve

[oldbutnotslow]

Mankee Ive done loads of these and achieved varying success in the early days.

As has been said there are a number of post about this one of which I wrote some time ago I cant find the post (well there is a surprise) but because of the incosistancy of the early attempts I managed to speak to the technical depatment at the foam manufacturers who sent me the following.

GENERAL INFORMATION ON MIXING AND USING

TRIPOR SYSTEMS

TRIPOR IS A RANGE OF 2-PACK POLYURETHANE POUR-IN-PLACE

SYSTEMS, SOLD IN PACKAGES FROM 1 kg TO 250 kg IN WEIGHT. ALMOST

ALL SYSTEMS USE THE SAME COMPONENT B (ISOCYANATE), THE

CHARACTERISTICS OF THE FOAM PRODUCED ARE DETERMINED BY THE

CHOICE OF COMPONENT A.

WHILST IT IS POSSIBLE TO MEASURE OUT THE COMPONENTS BY

VOLUME, IT IS NOT GENERALLY RECOMMENDED BECAUSE IT IS NOT

STRAIGHT FORWARD TO CALCULATE THE VOLUMES REQUIRED AND IT

IS VERY EASY TO BE A LONG WAY “OFF RATIO” AND END UP WITH

INFERIOR IF NOT UNSTABLE FOAM. IT IS THEREFORE BEST TO

MEASURE BY WEIGHT, AND, IF POSSIBLE, TO WEIGH THE SECOND

COMPONENT INTO THE FIRST, TO AVOID THE NECESSITY TO “WET-OUT”

THE POURING CONTAINER.

BEFORE USING THE COMPONENT A IT SHOULD BE PRE-MIXED TO

AERATE IT WHICH WILL HELP GIVE A BETTER MIX AND A FINER

CELLED FOAM STRUCTURE.

THE CHOICE OF MIXER TO BE USED WILL BE DETERMINED BY THE

AMOUNT TO BE MIXED, THE MIXING VESSEL AND THE AVAILABILITY

OF POWER. MIXING BY HAND, ALTHOUGH POSSIBLE, IS NOT

RECOMMENDED.

FOR QUANTITIES UP TO 25kg, AN ELECTRIC DRILL OF 550 WATTS OR

GREATER, REVOLVING AT 2000rpm OR GREATER, SHOULD BE

ADEQUATE, WHEN COMBINED WITH A SUITABLE STIRRER. THE MAJOR

D.I.Y. CHAINS SELL A REASONABLE MODEL, DESCRIBED AS A “BLACK &

DECKER PAINT STIRRER”.

QUANTITIES LARGER THAT 25kg WILL REQUIRE A MORE POWERFUL

MOTOR, AND AS THIS WILL USUALLY MEAN A REDUCTION IN

ROTATIONAL SPEED THERE WILL HAVE TO BE A CONSEQUENTIAL

INCREASE IN STIRRER DIAMETER, TRIDENT USE A 1200W DRILL

REVOLVING AT 1025rpm WITH AN 8” DIAMETER PROPELLER TO MIX UP

TO 60kg.

A USEFUL GUIDE TO THE SUITABILITY OF THE STIRRER IS THAT IT

SHOULD MIX THE RELEVANT AMOUNT OF COMPONENT A TO A WHITE

FROTHY CONSISTENCY IN THE MIXING TIME WHICH WILL BE USED FOR

FOAMING.

TEMPERATURES ARE A SIGNIFICANT FACTOR IN MIXING, 15-25 Deg. C IS

THE RECOMMENDED RANGE. LOWER TEMPERATURES GIVE HIGHER

MATERIAL VISCOSITIES, BUT MIXING CAN BE CARRIED OUT FOR

LONGER, WHEREAS HIGHER TEMPERATURES GIVE LOWER VISCOSITIES

BUT FASTER REACTIVITY, 18-20 Deg. C IS USUALLY A GOOD

COMPROMISE.

THE ACTUAL MIXING TIME TO BE USED WILL BE A COMPROMISE

BETWEEN THE TIME TAKEN TO GIVE THE BEST POSSIBLE MIX AND THE

TIME REQUIRED TO POUR THE MIXTURE INTO THE CAVITY. FOR

SMALLER QUANTITIES (<5kg) AT 20 Deg C THE TOTAL MIXING TIME

SHOULD NOT BE MUCH MORE THAT THE CREAM TIME STATED ON THE

TECHNICAL DATA SHEET, LARGER QUANTITIES WILL HAVE TO BE

ASSESSED BY TRIAL AND ERROR, BUT ALL FOAM PRODUCED SHOULD

HAVE A FINE EVEN CELL STRUCTURE.

CONTAINERS OF CHEMICALS SHOULD BE KEPT SEALED WHEN NOT

ACTUALLY IN USE, AS THE COMPONENT A WILL ABSORB ATMOSPHERIC

MOISTURE CAUSING LOWER DENSITY FOAM AND POSSIBLE

INSTABILITY, WHILST THE COMPONENT B WILL REACT WITH MOISTURE

TO GIVE A SOLID PRODUCT, GIVING SKIN ON THE LIQUID SURFACE OR

LUMPS IN THE CONTAINER.

POLYURETHANE FOAM WILL GIVE BETTER PROPERTIES AND

PERFORMANCE IF IT IS “OVERPACKED” OR RESTRAINED AS MUCH AS IS

REALISTICALLY POSSIBLE RATHER THAN ALLOWED TO RISE WITHOUT

ANY RESTRICTION.

BEFORE USING ANY SYSTEM IT IS IMPORTANT TO READ THE

RELEVANT MATERIAL SAFETY DATA SHEETS AND ENSURE THAT

THE MATERIALS ARE USED SAFELY.

The Key is temperature weight and how you mix the foam. I use a mixer in an electric drill'

Put both tins in the heating cupboard for a couple of hours before you start.

Mix both parts before you pour them together to get air into them and mix them again until it goes creamy (cream time)You really need another person to pour for you as the 'cream time' is limited

I would always pour in 2 parts as its easier to get the bits out of the car. I also use some cardboard to cover the harness anchor points and to restrict the foam from going too far forward on the bottom Similarly you need to have your foot on the clutch at some point as has been said otherwise it will be uncomfortable to drive once it hardens. The foam also need to be restricted from over expanding. ie you dont leave the plastic bag open during the setting time.Fold it over so that the foam becomes tight in the bag.

I always buy a cheap exercise mat and cut this to fit under the bag Not in it. This gives your arse a little bit of comfort! 

Last a warning. This stuff sticks to anything it touches including skin and is the very devil to get off so use gloves and wear some old clothes.

 

Ok yes the foam does get very hot around your gonads!  We have had temps around 40 degrees. 

[tbird]

Just to confirm we haven't lost The famous Mike Bees canoe tale

Tim

[Tony Whitley]

MOST IMPORTANT: Do make sure you set up a video camera before you do it